1. Field of the Invention
The present invention relates to a method and apparatus for cleaning a structure, such as a milk tank, and more particularly, to such a method and apparatus where the apparatus is positioned within the milk tank to spray a cleaning liquid, such as water, upwardly and outwardly against the interior surface of the tank wall.
2. Background Art
In general, the dairy industry has very stringent sanitation requirements. For example, any equipment which comes in contact with the milk must be arranged so that it can be thoroughly cleaned quite regularly. Thus, the milk tanks which carry the milk from the dairy farms to a collecting location must have the interior of the tank washed down at regular intervals.
Another requirement for equipment used in the dairy industry is that the component parts of the equipment must be arranged so that all surfaces of these parts can be thoroughly cleaned, thus avoiding the potential problem of contaminating material being lodged in cracks, crevices, or somewhat inaccessible areas which cannot be easily cleaned. This makes it necessary for the component parts to be easily disassembled for thorough cleaning, or for the components to be "self-cleaning" in that wash water passing through the apparatus performs the cleaning.
The common prior art way of accomplishing the washing of the interior of the milk tank is to place an elongate pipe into the interior of the tank, and to provide this pipe with discharge nozzles at spaced locations along the length of the pipe. One type of nozzle which is commonly used is a "spray ball", which is a spherical member having a plurality of through openings which spray the cleaning liquid (generally water) upwardly and outwardly against the tank interior surface. However, not only are these spray balls quite expensive to manufacture, but the discharge openings can easily be plugged.
Another type of prior art nozzle is one where there is a spiral-like element extending upwardly from an upward opening in the pipe. The water flowing upwardly through the pipe opening is diverted by this spiral-like element to spray outwardly and upwardly against the tank interior. Unfortunately, this nozzle is also expensive to manufacture.
A search of the patent literature has disclosed a number of patents relating generally to spray nozzles or discharge nozzles for a variety of applications. While these are not considered to be directly relevant to the problems toward which the present invention is directed, these are cited below to insure that there is a full disclosure of any prior art of possible relevance.
U.S. Pat. No. 4,339,081, Lindquvist, illustrates a device to be used, for example, as a shower nozzle. There is an insert that fits in a head portion and is retained in the head portion by a screw. The insert is formed with grooves around its outer surface to provide for the flow of water, and the inwardly facing surface of the head portion has similar grooves.
U.S. Pat. No. 3,874,597, Stephens, et al, shows a watering system to be used in various types of agricultural applications. There is a collapsible tube having opposed openings on opposite sides thereof. There is a flow control member having two head portions on its opposite ends, with these two head portions being positioned outside of the flexible tube, and the shank of the flow control member extending through the interior of the tube. Liquid in the tube flows outwardly from the tube and by at least one of the head portions.
U.S. Pat. No. 3,462,085, Nugarus, shows a nozzle where there is a generally cone-shaped deflecting member which discharges the liquid outwardly.
U.S. Pat. No. 2,128,552, Rader et al, also shows a cone-shaped discharge member in a sprinkler head. Such a discharge device is also shown in U.S. Pat. No. 1,510,930, Enell.
U.S. Pat. No. 1,112,622, Jones, shows an irrigating device having a discharge end positioned outside the pipe, and a anchor or retaining member located on the inside surface of the pipe. This is used for subsoil irrigation and is designed to prevent foreign matter from entering into the pipe.
Finally, U.S. Pat. No. 3,188,238, Lyon, is generally representative of a spray system used to clean the interior of a tank.